Project: upgrade my Maruzen CA870

[highny]

Hello guys. This is my second attempt in upgrading an airsoft gun.
The first time totally trashed my AEG... But this time, I'm going old school and upgrading a Maruzen CA870!

The first question is: Where the HECK do I find internal parts(inner barrel, spring, hopup) for this old shotgun?!...

Most of the popular website like WGC, Ehobby, airsoftparts, even redwolf don't carry any of these or have been "DISCONTINUED"!...... The most stuff they have that can be search under "870" are external parts.

Based on my last AEG upgrade, I tried too hard to make it perfect and end up ruin the gun. This time I'm only going to upgrade the inner barrel and maybe increase to the "medium" length outer barrel. The Medium outer barrel will use an 400mm inner barrel.

I remember, changing the length of inner barrel will require changing the type of the cylinder.
Question two: Does this affect a spring shotgun?

I'm using the adjustable stock(look like the m4 adjustable stock) version, which is annoying because even with the rail installed, looking through my red dot is a real pain! I envy the benelli m3 super 90 with their full stock and the adjustable version. I know there's a full stock for the CA870, but it's not adjustable.
Third question: Is there anyway to modify the m4 adjustable stock to bend a 330 degrees(or -30 degrees)? If so, list the tools that you might use to complete this task.

I've heard that someone in the pass manage to convert the fix hop up into an adjustable hop up.
Forth question: Is it possible to convert? If so, how difficult would you say it is?


Thank you for reading. I'm looking forward to reading your replies.

[wildcard]

Originally Posted by highny

Hello guys. This is my second attempt in upgrading an airsoft gun.
The first time totally trashed my AEG... But this time, I'm going old school and upgrading a Maruzen CA870!

The first question is: Where the HECK do I find internal parts(inner barrel, spring, hopup) for this old shotgun?!...

Most of the popular website like WGC, Ehobby, airsoftparts, even redwolf don't carry any of these or have been "DISCONTINUED"!...... The most stuff they have that can be search under "870" are external parts.

Based on my last AEG upgrade, I tried too hard to make it perfect and end up ruin the gun. This time I'm only going to upgrade the inner barrel and maybe increase to the "medium" length outer barrel. The Medium outer barrel will use an 400mm inner barrel.

I remember, changing the length of inner barrel will require changing the type of the cylinder.
Question two: Does this affect a spring shotgun?

I'm using the adjustable stock(look like the m4 adjustable stock) version, which is annoying because even with the rail installed, looking through my red dot is a real pain! I envy the benelli m3 super 90 with their full stock and the adjustable version. I know there's a full stock for the CA870, but it's not adjustable.
Third question: Is there anyway to modify the m4 adjustable stock to bend a 330 degrees(or -30 degrees)? If so, list the tools that you might use to complete this task.

I've heard that someone in the pass manage to convert the fix hop up into an adjustable hop up.
Forth question: Is it possible to convert? If so, how difficult would you say it is?


Thank you for reading. I'm looking forward to reading your replies.

I have the G&P modified version of the Maruzen CA870 unfortunately this particular Shotty have a fixed hop up unit, I have heard of a mod that will fit but so far have no luck in gaining any info.
As for parts any G&P M870 parts will fit, in fact the G&P model of this shotty is called G&P M870. you can still get various retractable stock and internals for this shotty but only G&P makes them.

[coach]

Originally Posted by wildcard

this particular Shotty have a fixed hop up unit, I have heard of a mod that will fit but so far have no luck in gaining any info.

I was chatting with Drake about adding a hopup on the m500. similar situation that it's a fixed hopup or rather none.

adding one is apparently easy but you'd have to source out the parts and mod the shotty.

Originally Posted by Drake

snip
In the "early days" they use to have bolt action sniper rifles with no hopup. There use to be tutorials on how to add hopup to them. Don't remember which rifle it was nor been able to locate one of the tutorials. But I recall it being relatively simple.
/snip

[wildcard]

Originally Posted by coachster

I was chatting with Drake about adding a hopup on the m500. similar situation that it's a fixed hopup or rather none.

adding one is apparently easy but you'd have to source out the parts and mod the shotty.

the spacing in and around the barrel is too tight and the space between the barrel and the receiver is too short to accomodate any hop up unit the only way I can see it being done is actualy tapping a hole on the outer barrel and use some sort of screw to push down a nub to act as a semi adjustable hop up,
the shotty is too nice right now for me to drill anything into it so I'll wait

[coach]

Originally Posted by wildcard

the spacing in and around the barrel is too tight and the space between the barrel and the receiver is too short to accomodate any hop up unit the only way I can see it being done is actualy tapping a hole on the outer barrel and use some sort of screw to push down a nub to act as a semi adjustable hop up,
the shotty is too nice right now for me to drill anything into it so I'll wait

yeah I hear ya. I figured drilling a hole in the outer barrel is probably the only way to access it or adjust it.

I might try to do this on my m500 or just go with a tightbore to try to increase my range a bit. (even if it reduces the spread on impact)

[highny]

I had an idea based on the fact the the hop up for this is just a small rubber piece which can be easily taken out and lose it. So my idea is, remove the outer barrel and there should be a small hole on the receiver that has a pin in it. Be removing it, then drill and thread the hole, I can easily glue that rubber hop up onto a screw and just screw down or up to adjust the hop up. Anyone get what I'm saying?

[Skruface]

Originally Posted by highny

I had an idea based on the fact the the hop up for this is just a small rubber piece which can be easily taken out and lose it. So my idea is, remove the outer barrel and there should be a small hole on the receiver that has a pin in it. Be removing it, then drill and thread the hole, I can easily glue that rubber hop up onto a screw and just screw down or up to adjust the hop up. Anyone get what I'm saying?

This is exactly what I did to my CA870, only I used a drop of caulking silicone on the end of an allen screw. Worked like a charm.

Originally Posted by highny

The first question is: Where the HECK do I find internal parts(inner barrel, spring, hopup) for this old shotgun?!...

The has been nothing available for years other than the odd G&P release, and those are mostly cosmetic - no one's had ANGS parts stocked for at least 3-4 years. Learn to live with what you have. I read somewhere that 9mm APS-2 springs work if you cut them down a few coils. Be aware that the piston assembly is plastic, and not designed to handle a lot of stress, and that replacement piston assemblies have been a absolute bitch to find in the past. G&P makes great front end kits that come with an inner barrel as well as metal bodies; I had a G&P Long Barrel kit and it outranged a stock TM VSR-10. Dee's Custom barrels also makes custom tightbores IIRC.

Originally Posted by highny

I remember, changing the length of inner barrel will require changing the type of the cylinder.
Question two: Does this affect a spring shotgun?

Nope, not on the CA870.

Originally Posted by highny

Third question: Is there anyway to modify the m4 adjustable stock to bend a 330 degrees(or -30 degrees)? If so, list the tools that you might use to complete this task.

Probably won't work. Either get a riser for your RDS, or put on an RIS and mount your RDS further forward.

Originally Posted by highny

I've heard that someone in the pass manage to convert the fix hop up into an adjustable hop up.
Forth question: Is it possible to convert? If so, how difficult would you say it is?

See above. Use a small hex screw and tap the existing hole properly.

[highny]

Originally Posted by Skruface

This is exactly what I did to my CA870, only I used a drop of caulking silicone on the end of an allen screw. Worked like a charm.

Wow! Would it be possible to get some picture on what you did?...

Originally Posted by Skruface

I read somewhere that 9mm APS-2 springs work if you cut them down a few coils. Be aware that the piston assembly is plastic, and not designed to handle a lot of stress, and that replacement piston assemblies have been a absolute bitch to find in the past. G&P makes great front end kits that come with an inner barrel as well as metal bodies; I had a G&P Long Barrel kit and it outranged a stock TM VSR-10. Dee's Custom barrels also makes custom tightbores IIRC.

Dee's custom barrels? Is that a company that custom make barrels? Also, How tight would be good using metal tech bbs? I'm assuming 6.03mm-6.04mm? correct me if I'm wrong please.

[Skruface]

Originally Posted by highny

Wow! Would it be possible to get some picture on what you did?...

Sadly, gun was sold like 2 summers ago, and I have no pics of the mod.

Originally Posted by highny

Dee's custom barrels? Is that a company that custom make barrels?

Yes.

Originally Posted by highny

Also, How tight would be good using metal tech bbs? I'm assuming 6.03mm-6.04mm? correct me if I'm wrong please.

Dee's does 6.01 barrels IIRC. Their old website appears to no longer work. I know Spartan Imports and ASGI carry them.